In the manufacture of large size fiber reinforced composite structures, such as those used in aerospace and vehicle (e.g. bus) structures, a dry reinforcement, such as a sandwich of foam between plies or layers of glass fiber, is laid up in a female mold and an infusion medium is carefully aligned and placed on the reinforcement to facilitate infusion of chemically catalyzed liquid resin evenly across and through the reinforcement. The infusion medium includes a peel ply adjacent the reinforcement to prevent sticking to the resin infused reinforcement.
A flexible, gas impermeable bag is placed around the entire female mold, and a relative vacuum is drawn in the bag to a degree that ambient pressure external of the bag compresses the reinforcement in a manner to substantially reduce its cross-sectional thickness. A chemically catalyzed resin is pumped into the "bagged" mold through numerous individual resin supply lines or conduits. A large number of resin supply lines is necessary to insure distribution of the resin through the reinforcement before the resin cures or hardens in-situ by virtue of the chemical catalyst present. When resin curing or hardening is completed in the female mold, the flexible bag, the infusion medium, and resin supply lines all must be removed and disposed of in an environmentally acceptable manner.
Although the resin infusion method described above produces high-quality reinforced composite structures, it is disadvantageous in that excess resin waste is produced. In particular, since the resin cannot be removed from the resin supply lines before the resin cures or hardens in the mold, both the resin supply lines and resin in the lines must be destroyed or disposed of as hazardous waste. Moreover, curing or hardening of the chemically catalyzed resin in the mold may occur prematurely, resulting in a lack of repeatability of one composite structure to the next. The infusion method described above is further disadvantageous in that intensive manual touch labor is needed from lay-up of the reinforcement and infusion medium in the female mold and their careful alignment prior to injection of resin followed by removal of the flexible bag, infusion medium and resin supply lines after resin injection and curing or hardening. This manual labor increases cycle time and cost to manufacture reinforced composite structures.
An object of the present invention is to provide a resin infusion method and apparatus that overcome these aforementioned problems and disadvantages.